The present invention relates to a transmitting and/or receiving antenna composed of two or more individual antennas of any desired polarization, which may even be a frequency dependent polarization.
The term "antenna" as used herein is intended to encompass antennas having reflectors as well as antennas not having reflectors.
As is known, a high gain antenna array requires a large number of individual antennas. In order to obtain the desired radiation pattern characteristics, the individual antennas are combined into directional beam networks, the summing members preferably being hybrids, i.e. components having decoupling properties which generally serve to combine or divide voltages at the same frequency with respect to amplitude or phase, if required, with a weighting of the individual voltages.
Antenna arrays having defined polarization properties require a certain alignment of their individual antennas. Antenna arrays intended to have a vertical polarization are usually constructed of vertically polarized individual antennas and antenna arrays which are to exhibit horizontal polarization are designed with horizontally polarized individual antennas. If both polarizations are to be available simultaneously, this is usually realized by employing individual antennas in a crosswise arrangement with the same phase center.
The known antenna arrangements composed of individual antennas with undefined polarization have the drawback that in addition to the desired polarization, there occurs an undesirable transverse polarization, so that when such antenna arrangements are used, for example, for direction finding purposes, it is easily possible that bearing errors might occur.